The long-range goal of this Program Project is to develop vaccine strategies and immunoprophylaxis against intrapartum transmission of HIV clade C by combining passive immunization with synergistic combinations of human neutralizing monoclonal antibodies with active vaccination with a DNA prime/protein boost strategy. The overall objectives for this Core are to provide the required experimental animals and support services needed to facilitate completion of the objectives outlined in Project 2 (Passive and Active Immunization) and Project 3 (DNA Prime/Protein Boost Vaccination). This will include provision of newborn and juvenile retrovirus-free (SIV/ STLV-1, SRV) rhesus macaques from the Yerkes macaque breeding colonies; oral and HIV macaques; immunizations of the experimental animals with DNA or protein immunogens; use of monoclonal antibodies alone or in combination with active immunization; viral challenge of the immunized animals; daily monitoring of the experimental animals; periodic physical examinations of the experimental animals and blood collections for hemogram and immunologic evaluations and for shipment to Drs. Ruprecht and Rasmussen's laboratories for in vitro studies; performance of CBCs and flow cytometry evaluations to determine lymphocyte subsets; and the performance of complete gross and histologic evaluation of all experimental animals that die or that are sacrificed during the course of the study. Provision of these resources and support services will facilitate the development and testing of the AIDS immunization strategies proposed in this Program Project. These studies will also document the infectivity and pathogenicity of the chimeric simian-human immunodeficiency virus encoding the env gene of HIV clade C, and will allow an assessment of vaccine efficacy with respect to either the prevention of infection (sterilizing immunity) or modification of post challenge virus load.